Logo of the Physikalisch-Technische Bundesanstalt

Single-charge Circuits

Working Group 2.42

Fabrication of sub-µm metallic devices

Angle evaporation

This technique starts with the fabrication of a shadow mask. Two metallic layer are evaporated onto this mask under two different angles. The tunnel barrier is created by an oxidation process after the deposition of the first metallic layer.

This procedure allows the in situ fabrication of tunnel junctions. The junction size can be adjusted by a variation of the evaporation angels. Disadvantages of this technique are the parasitic shadows and the limitation to low melting materials, e.g. Aluminium.

The extension of the shadow evaporation technique to three evaporation steps under three different angles enables the fabrication of Single-electron pumps with improved performance by the in situ integration of resistors.